A digital model to identify vaccine-eligible frail patients: the CareVax pilot study

Background

Vaccine-preventable diseases contribute to morbidity, mortality, and healthcare costs among frail patients. The 2022–2025 Italian National Vaccine Prevention Plan promotes expanded vaccination coverage, yet no fully automated systems exist to identify vaccine-eligible patients in hospital settings. CareVax, a project funded within the Italian National Complementary Plan, addresses this gap through a digitally integrated hospital-based vaccination model.

Methods

CareVax is a single-arm pilot study conducted at Fondazione Policlinico Universitario A. Gemelli IRCCS. The project developed a SAS-based algorithm using a decision tree based on age, ICD-9-CM codes, and regional exemption codes to automatically identify frail patients eligible for vaccination against influenza, pneumococcus, Herpes Zoster, SARS-CoV-2, and hepatitis B. Physicians review lists of eligible patients, contact them, and schedule vaccination accordingly. The algorithm is being validated across several clinical departments by assessing agreement with clinical judgement, operational feasibility, and patient adherence to personalized vaccination pathways.

Results

Preliminary results show 95% concordance between the algorithm and clinical judgement. Of 621 patients approached, 411 (66.2%) accepted screening (median age 59 years). Among enrolled patients, 22.9% consented to vaccination, 23.1% had not yet decided, and 54.0% dropped out due to refusal (47.3%) or non-reachability (45.9%). Vaccination uptake varied significantly by department (p = 0.002), with the highest uptake in Nephrology (40.2%) and the lowest in Geriatrics (10.9%). In the first year, 230 vaccine doses were administered.

Conclusions

CareVax shows the feasibility of integrating an algorithm into hospital workflows to identify vaccine-eligible frail patients. Its scalable architecture offers a replicable model for digital public health, although targeted strategies are needed to reduce drop-out and improve vaccine acceptance.

Key messages

• Frail patients remain under-vaccinated due to fragmented care pathways and lack of systematic identification of vaccine eligibility and proactive vaccination offer.

• A SAS-based automated algorithm integrated into hospital workflows is a feasible and scalable approach to identify vaccine-eligible frail patients, supporting proactive prevention.